1. The Field of the Invention
The present invention generally relates to optical communications systems. More particularly, the present invention relates to a system of producing and modulating optical signals for transmission via an optical communications network.
2. The Related Technology
Fiber optic technology is increasingly employed as a method by which information can be reliably transmitted via a communications network. Networks employing fiber optic technology are known as optical communications networks, and are marked by high bandwidth and reliable, high-speed data transmission.
Optical communications networks typically employ optical transceivers in transmitting information via the network from a transmission node to a reception node. At the transmission node, typical optical transceivers receive an electrical data signal from a network device, such as a computer, and convert the electrical data signal to a modulated digital optical data signal using a laser. Thus, production of a pulse of light by the laser can correspond to a digital “one” or “zero,” while no pulse corresponds to a “zero” or “one,” respectively, according to the configuration of the network. The modulated optical data signal produced by the laser can then be transmitted in a fiber optic cable via the optical network, such as a LAN backbone, for instance.
The optical data signal is transmitted to and received by a reception node of the network. Once received by the reception node, the optical data signal is fed to another optical transceiver for conversion into electrical data signals. The electrical data signals are then forwarded to a host device, such as a computer, for processing. The optical transceivers described above have both signal transmission and reception capabilities; thus, the transmitter portion of the transceiver converts an incoming electrical signal into an optical signal, whereas the receiver portion of the transceiver converts an incoming optical signal into an electrical signal.
The majority of components included in the optical transceiver are disposed on a printed circuit board (“PCB”). These components include a controller, which governs general operation of the transceiver, a laser driver for controlling operation of the laser in the transmitter portion, and a post-amplifier for controlling the conversion of incoming optical signals into electrical signals in the receiver portion. These components are typically configured as integrated circuits on the PCB.
Despite their utility, traditional laser-based transceivers are confronted by various challenges. Among these is laser chirp, which refers to the drifting of the frequency of the optical signal produced by the transceiver. Laser chirp is temperature dependent: as the laser temperature varies during operation, the frequency drift of the light signal can likewise vary. As it affects the quality of the optical signal produced by the transceiver, laser chirp can represent a significant problem to be overcome during transceiver operation.
To acceptably deal with the above, lasers must be designed to mitigate the effects of laser chirp and related challenges. Unfortunately, this requires that the transceiver be implemented with a variety of devices, including temperature controllers, laser bias controls, wavelength locking components, and other circuitry for adjusting transceiver components as necessary. Not only does this increase the cost of the transceiver in terms of added manufacturing steps, it also increases the complexity of the device. Furthermore, these additional components can sometimes fail to control the laser's operation as would be desired, thereby introducing issues of reliability into transceiver performance.
A need therefore exists for an optical system that can reliably produce modulated optical signals without the attendant problems observed in known systems, as explained above.